1. Field of the Invention
This invention relates to cosmetics such as foundations, powders and makeup cosmetics, improved in spreadability and inunctionability.
2. Description of the Prior Art
Cosmetics mixed with powders are conventionally in wide use. These, however, have a poor spreadability and inunctionability especially to the skin, and are sought to be improved in such properties. To cope with such a demand, proposed are an inorganic composite powder surface-treated with a fluorine compound (see Japanese Laid-open Publication (Kokai) No. 6-79163), a powder surface-treated with methylhydrogenpolysiloxane or the like (see Japanese Laid-open Publication (Kokai) No. 5-112430), a hydrophobic powder surface-coated with an acrylic silicone type graft copolymer (see Japanese Laid-open Publication (Kokai) No. 5-339125), an extender pigment comprising potassium titanate coated with a metal oxide (see Japanese Laid-open Publication (Kokai) No. 5-163117), a chitosan powder surface-treated with hydrogenpolysiloxane (see Japanese Laid-open Publication (Kokai) No. 5-86102), a pigment comprising nitride microscopic lamellar substrates coated with a dye/metal oxide (see Japanese Laid-open Publication (Kokai) No. 5-279594), a flaky silica (see Japanese Laid-open Publication (Kokai) No. 6-87720), an ultrafine powder of collagen fibers (see Japanese Laid-open Publication (Kokai) No. 6-107522), a titanium oxide compound having photochromic properties (see Japanese Laid-open Publication (Kokai) No. 5-17152), and a polyamide powder of spherical fine particles (see Japanese Laid-open Publication (Kokai) No. 5-70598). These powders, however, have disadvantages that they not only have an insufficient spreadability to the skin but also have an unstable quality because of a difficulty in manufacture.
A makeup cosmetic is also proposed which has been mixed with polymethylsilasesquioxane as a silicone resin powder (see Japanese Laid-open Publication (Kokai) No. 63-297313). In the case of this cosmetic, it is a little improved in spreadability but has a poor inunctionability.
Silicone rubber powder is also known as a cosmetic powder. This powder has a good softness in itself, but can not improve the spreadability or inunctionability when mixed in cosmetics.
An object of the present invention is to overcome the disadvantages the prior art has had as stated above, and to provide a cosmetic improved in spreadability and inunctionability.
To achieve the above object, the present invention provides a cosmetic comprising spherical hydrophobic fine silica particles having an average particle diameter of from 0.01 to 5 xcexcm, which are obtained by introducing an R2SiO3/2 unit (wherein R2 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms) to the surfaces of hydrophilic fine silica particles comprising an SiO2 unit to obtain hydrophobic fine silica particles, and introducing an R13SiO1/2 unit (wherein R1""s may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms) to the surfaces of the resultant hydrophobic fine silica particles to make the particles more hydrophobic.
Spherical Hydrophobic Fine Silica Particles
The spherical hydrophobic fine silica particles used in the cosmetic of the present invention is a product obtained by introducing an R2SiO3/2 unit (wherein R2 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms) to the surfaces of hydrophilic fine silica particles comprising an SiO2 unit to obtain hydrophobic fine silica particles, and introducing an R13SiO1/2 unit (wherein R1""s may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms) to the surfaces of the resultant hydrophobic fine silica particles to make the particles more hydrophobic. From the viewpoint of an improvement in spreadability and inunctionability, the spherical hydrophobic fine silica particles thus obtained must have an average particle diameter within the range of from 0.01 to 5 xcexcm, and preferably from 0.05 to 1 xcexcm. If their average particle diameter is smaller than 0.01 xcexcm, the cosmetic may have a poor spreadability, and, if larger than 5 xcexcm, a poor inunctionability.
The monovalent hydrocarbon group represented by R2 in the R2SiO3/2 unit may include, e.g., alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl and decyl; aryl groups such as phenyl, tolyl and naphthyl; aralkyl groups such as benzyl and phenetyl; alkenyl groups such as vinyl, allyl, hexenyl and cyclohexenyl; and any of these groups at least part of hydrogen atoms of which has been substituted with a halogen atom such as a fluorine atom, as exemplified by a trifluoromethyl group and a heptadecafluorodecyl group. Preferably, R2 includes methyl, ethyl, propyl and butyl groups.
The monovalent hydrocarbon group represented by R1 in the R13SiO1/2 unit may include, e.g., alkyl groups such as methyl, ethyl, propyl, butyl, pentyl and hexyl. Preferably, R1 includes methyl, ethyl, propyl and butyl groups.
Specifically, the present spherical hydrophobic fine silica particles are produced through the following steps:
the steps of subjecting at least one compound selected from the group consisting of a tetrafunctional silane compound represented by the general formula (I):
Si(OR3)4xe2x80x83xe2x80x83(I)
wherein R3""s may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, a partial hydrolysis-condensation product thereof and a mixture of these, to hydrolysis and condensation in a mixed solvent of water and a hydrophilic organic solvent (e.g., methanol or ethanol) containing a basic substance such as ammonia or an organic amine, to prepare a hydrophilic solvent dispersion of hydrophilic fine silica particles, adding water to the resultant dispersion, and thereafter evaporating the hydrophilic organic solvent to convert the dispersion into an aqueous dispersion to hydrolyze the remaining alkoxyl groups completely;
the step of adding to the resultant aqueous dispersion of hydrophilic fine silica particles at least one compound selected from the group consisting of a trifunctional silane compound represented by the general formula (II):
R2Si(OR4)3xe2x80x83xe2x80x83(II)
wherein R2 represents a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R4""s may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, and a partial hydrolysis-condensation product thereof, to treat the hydrophilic fine silica particle surfaces with it to obtain hydrophobic fine silica particles, thus the R2SiO3/2 units being introduced onto the surfaces of the hydrophilic fine silica particles comprising SiO2 units to produce hydrophobic fine silica particles;
the step of converting the resultant aqueous dispersion of hydrophobic fine silica particles into a ketone solvent dispersion by adding a ketone solvent followed by evaporation of water; and
the step of adding to the resultant hydrophobic fine silica particle ketone solvent dispersion at least one compound selected from the group consisting of a silazane compound represented by the general formula (III):
R13SiNHSiR13xe2x80x83xe2x80x83(III)
wherein R1""s may be the same or different and each represent a monovalent hydrocarbon group having 1 to 6 carbon atoms, and a monofunctional silane compound represented by the general formula (IV):
R13SiXxe2x80x83xe2x80x83(IV)
wherein R1""s are as defined in the general formula (III), and X represents a hydroxyl group or a hydrolyzable group, to allow to react with silanol groups remaining on the hydrophobic fine particle surfaces, thereby the silanol groups being trialkylsilylated, i.e., the R13SiO1/2 units being introduced to the surfaces of the hydrophobic fine silica particles.
The spherical hydrophobic fine silica particles thus finally obtained are particles whose surfaces have been made more highly hydrophobic than the hydrophobic fine silica particles to which the R13SiO1/2 units have not been introduced. This spherical hydrophobic fine silica particles have no longer any residual reactive groups such as silanol groups and also are highly dispersible and less agglomerative, having a good fluidity, and hence can bring about good results for the object and effect of the present invention.
Examples of the tetrafunctional silane compound represented by the general formula (I) include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and tetrabutoxysilane. Examples of the partial hydrolysis-condensation product thereof include methyl silicate and ethyl silicate.
Examples of the trifunctional silane compound represented by the general formula (II) include trialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, hexyltrimethoxysilane, trifluoropropyltrimethoxysilane and heptadecafluorodecyltrimethoxysilane.
Examples of the ketone solvent include methyl ethyl ketone, methyl isobutyl ketone and acetyl acetone, and preferably methyl isobutyl ketone.
Examples of the silazane compound represented by the general formula (III) include hexamethyldisilazane. Examples of the monofunctional silane compound represented by the general formula (IV) include monosilanol compounds such as trimethylsilanol and triethylsilanol, monochlorosilanes such as trimethylchlorosilane and triethylchlorosilane, monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane, monoaminosilanes such as trimethylsilyldimethylamine and trimethylsilyldiethylamine and monoacyloxysilanes such as trimethylacetoxysilane.
Other Components
The cosmetic of the present invention is basically comprised of the spherical hydrophobic fine silica particles described above. Additional powders and other components such as binder oils, surface-active agents, perfumes, antiseptics and solvents which are usually used may optionally be mixed depending on uses such as foundations, creams, powder products and makeup cosmetics.
The additional powders may include, e.g., talc, titanium oxide, mica and zinc oxide. Any of these may be used alone or in combination of two or more types.
The binder oil may include, e. g., liquid paraffin, mineral oils, vegetable oils (such as lanolin and avocado oil) and low-viscosity silicone oil. Any of these may be used alone or in combination of two or more types.
As the surface-active agents, any anionic, cationic, nonionic or amphoteric surface-active agents may be used. Any of these may be used alone or in combination of two or more types.
The solvents may include, e.g., polyethylene glycol, polypropylene glycol, fatty acid esters and higher alcohols. Any of these may be used alone or in combination of two or more types.
The quantities of these optional components to be mixed may vary depending on the types of cosmetics. For example, in the case of foundations, it is suitable for additional powders to be mixed in an amount of from 1 to 1,000 parts by weight; the binder oil, from 1 to 100 parts by weight; the surface-active agent, from 0 to 100 parts by weight; and the solvent, from 1 to 1,000 parts by weight; based on 10 parts by weight of the spherical hydrophobic fine silica particles. In the case of makeup cosmetics such as eye shadow, it is also suitable for additional powders to be mixed in an amount of from 1 to 1,000 parts by weight; the binder oil, from 1 to 100 parts by weight; the surface-active agent, from 0 to 100 parts by weight; and the solvent, from 1 to 1,000 parts by weight; based on 10 parts by weight of the spherical hydrophobic fine silica particles. In the case of powder products such as deodorant powder, it is also suitable for the additional powder to be mixed in an amount of from 1 to 1,000 parts by weight; the binder oil, from 1 to 100 parts by weight; the surface-active agent, from 0 to 100 parts by weight; and the solvent, from 1 to 1,000 parts by weight; based on 10 parts by weight of the spherical hydrophobic fine silica particles.
Production of Cosmetics
The cosmetic of the present invention may be produced by conventionally known processes. For example, the spherical hydrophobic fine silica particles are blended alone or in combination with an additional powder by means of a mixing machine such as a Henschel mixer, a super mixer, a V-blender, an automated mortar or a Nauta mixer. The mixture thus obtained is further mixed with a binder oil, a surface-active agent and so forth having separately dissolved or dispersed in a suitable solvent, by means of a mixing machine such as a ribbon blender or a planetary mixer. Thereafter, this final mixture obtained may optionally be molded by, e.g., press molding to obtain the cosmetic.
Uses
The cosmetic of the present invention is usable as, but not limited to, e.g., foundations; cream of various types; powder products such as deodorant powder, presto powder, face powder and shaving powder; makeup cosmetics such as rouge, eye shadow, mascara and eyeliner; cleaning preparations such as dry shampoo and makeup removers; and sweat controlling preparations of roll-on types or spray types.